The Great Purge
prompted in Hook an increasing ambivalence toward Marxism. In 1939,
Hook formed the Committee for Cultural Freedom, a short-lived
organization that set the stage for his postwar politics by
opposing "totalitarianism" on the left and right.
By the time of the Cold
War Hook was a prominent anti-Communist,
although he continued to consider himself a democratic socialist throughout
his life.

In the 1960s, Hook was a frequent critic of the New Left attaining notoriety
for his outspoken support of the Vietnam War and for his defense of
Governor Ronald Reagan's decision to fire Angela Davis from her position as a
professor at UCLA because of her membership in the Communist Party
(she was later rehired). He ended his career in the 1970s and 1980s
as a fellow of the conservativeHoover Institution in Stanford,
California.